I fell into writing about health shortly after grad school, where I realized I didn't want to work in a lab for the rest of my life! My areas of interest are the brain and behavior, as well as what influences the decisions we make about our health, and how the media helps and hinders people's understanding of health issues. As an undergraduate, I studied English Literature and Biopsychology at Vassar College, and got my PhD in Biopsychology and Behavioral Neuroscience at CUNY's Graduate Center in New York City, where I grew up and live now. My day job is as Associate Editor with the health website, TheDoctorWillSeeYouNow.com. My work has appeared in several other publications, including TheAtlantic.com and YogaGlo.com, and I'm particularly excited to join the Forbes health team. Email me at alicegwalton [at] gmail [dot] com .

Why Meat And Protein Are Not The Same

In the last week alone, there’s been enough conflicting research on meat to turn a person veggie (and that might not be a bad way to go). Among the most recent study results, animal protein will give you heart disease and breast cancer, and possibly kill you. On the upside it may save you from a stroke, and it helps build muscle. There are obviously some caveats at play. One issue is that even within a given category (e.g., animal protein), the health effects can vary greatly. The other question is whether we can have too much protein overall, even of the “purest” kind. While eating more protein isn’t necessary for most Americans – we take in an awful lot already – where we get our protein is the question.

So what do we do? The answer actually hasn’t changed very much over the years, despite the apparent uptick of conflicting evidence: Eat adequate but not excessive amounts of protein, certainly from plants, and possibly from fish, eggs, and poultry. And if you’re going to indulge in red meat (and there is evidence that some people perhaps should), just about everyone advises to do it sparingly.

(Photo credit: Wikipedia)

Here’s a recap of the research in the last week. One study found that red meat was linked to an increase in the risk of breast cancer, in a study of over 88,000 nurses in the Nurses’ Health Study II. Nuts, beans, fish, and poultry, didn’t seem to pose the same risk, however, and poultry alone was linked to a lower risk of breast cancer.

Another study found, not surprisingly, the meat consumption was linked to heart disease in a study of 37,000 middle-aged men – but there was difference when the researchers broke it down and looked at processed vs. unprocessed meat. Men who ate mostly unprocessed red meat didn’t have any greater risk of heart disease, but men who ate mostly processed meats – hotdogs, sausages, and such – had a greatly increased risk of heart disease and cardiac-related death.

Finally, one study appeared at first glance to provide a ray of hope for the meat lover, finding that high-protein diets might lower the risk of stroke, likely for blood-pressure lowering reasons. Animal protein was associated with a significantly reduced risk of stroke in a meta-analysis of over 250,000 people. But again, a caveat: The authors say the findings do not extend to red meat, since it’s known to increase the risk of stroke. Therefore, headlines touting the fact that “protein lowers stroke risk!” along with a picture of steak are misleading, and readers should realize that the source really does matter.

There are a few reasons why protein may both healthy and unhealthy, depending on the type, amount, and stage of life you’re in. Proteins are made up of amino acids, which are critical in just about every element of our cells’ structure and function. Some amino acids can be made by the body, but others can’t, so we have to consume them. The presence or absence of these essential amino acids, of which there are nine, are what make a protein “complete” or “incomplete.” Animal sources of protein are typically complete – eggs, dairy products, and meat/poultry/fish. Vegetables generally offer only incomplete proteins, which is why it’s important for vegetarians to pair consume different plant sources. (Addendum: Several comments came in mentioning the fact that taking in all amino acids at once is not necessary. So vegetarians don’t need to “pair proteins” at every meal, but will likely get all the essential amino acids by just eating a variety of foods.)

So protein is essential, but in high doses, some have suggested it may also be detrimental. One reason is that it appears to trigger the production of a growth factor, IGF-I, which is linked to cancer cell proliferation. Some studies, like this recent one, have found that any type of protein, but animal protein in particular, is linked to an increased cancer risk. Valter Longo, who headed the study, says that “[a]lmost everyone is going to have a cancer cell or pre-cancer cell in them at some point,” says Longo. “The question is: Does it progress? Turns out one of the major factors in determining if it does is protein intake.”

The other issue is that we don’t eat protein alone: It comes with fats, carcinogens, and hormones. Red meat in particular seems to be in a class of its own. It has been shown in a number of studies to increase the risk for colon cancer; there is less evidence that other forms of cancer are connected to red meat. Although the mechanism isn’t totally clear, some researchers have suggested it’s the form of iron in red meat that may trigger the formation of cancer-causing N-Nitroso compounds. Others have suggested that it’s the heterocyclic amines (HCAs) — carcinogens are released when meat is cooked under higher temperatures. And red meat has been linked to heart disease many times over, but likely for reasons related to fat content, rather than protein.

So one issue is that meat and protein are not exactly interchangeable, since any kind of protein carries along with it lots of other compounds. Steak and turkey breast may have very different effects on the body. And again, the harder question is whether high doses of protein from any source pose health risks. Longo stresses that from his study, at least, all forms of protein were linked with cancer, even that from plants. “Keep in mind that for cancer, plant proteins at high levels are still associated with a 3-fold higher mortality. But this is not as bad as that for animal protein (4-fold). For overall mortality instead, the animal-to-plant switch makes a big difference.”

The protein-health connection will need a lot more research before we understand it completely. The effects of a single molecule in foods made of many, many molecules are very hard to isolate. In the meantime, keep protein intake moderate: Most organizations recommend swapping out red meat for other sources, and taking in about 46 grams per day for women, and 56 grams per day for men.

So have a little protein, but avoid the fats, hormones, and carcinogens, where you can. Plants, fish, and eggs are probably best, if you crave it, a burger every now and then probably won’t kill you. Of course, eating plant-based proteins also gives you the peace of mind that you’re not contracting Mad Cow Disease along with it. While the recent scare seems to be largely a technical glitch, and not any real biological cause for concern, the vegetarians out there will breathe a sign of relief that the issue doesn’t pertain to them.

Post Your Comment

Post Your Reply

Forbes writers have the ability to call out member comments they find particularly interesting. Called-out comments are highlighted across the Forbes network. You'll be notified if your comment is called out.

Comments

Another study found that what time of the day you consume your protein matters, at least for muscle-building purposes. Eating large portions at night (which a lot of people do, at dinnertime) was linked to poorer muscle synthesis than when it’s consumer earlier in the day.

why don’t you draw a distinction between grass fed or wild caught protein and what is sold in most grocery stores? at the very least it should be clarified in the studies where this red meat is coming from and how it’s grown. there is a huge health difference (specifically cows but also farmed fish) in grain fed and fattened “protein” with antibiotics and other chemicals and kept in contained conditions. all meat isn’t the same.

I seriously doubt there is much if any health difference in red meat. There is a taste difference and I prefer grass fed buffalo myself. Farmed fish do have a slight difference even if they are exposed to the same water but there isn’t enough evidence so far to say a farm raised salmon is not as healthy as a wild salmon (again, the wild salmon tastes better to me). I completely disagree with your statement “…and other chemicals” since everything on our planet is composed of chemicals and stating that is nothing more than food babe fear mongering.

Article should mention that “complete protein” is also a bit misguided. Your body does not require all amino acids to come from the same food source, only that you get all that you require. For example, mixing beans and rice will get you a complete set of amino acids whereas individually they will not. Your body also doesn’t always need all amino acids in the same meal.

“We’ve all heard that plant protein is ‘incomplete’ compared to meat protein, and that plant foods have to be carefully combined to make a “complete” protein. But that’s just an urban legend that was never based on science. The American Dietetic Association abandoned that idea decades ago. Susan Havala Hobbs, Ph.D, R.D. describes how the ADA discarded the protein combining idea:

‘There was no basis for [protein combining] that I could see…. I began calling around and talking to people and asking them what the justification was for saying that you had to complement proteins, and there was none. And what I got instead was some interesting insight from people who were knowledgeable and actually felt that there was probably no need to complement proteins. So we went ahead and made that change in the paper. [The paper was approved by peer review and by a delegation vote before becoming official.] And it was a couple of years after that that Vernon Young and Peter Pellet published their paper that became the definitive contemporary guide to protein metabolism in humans. And it also confirmed that complementing proteins at meals was totally unnecessary.8.5′ ”

http://michaelbluejay.com/veg/protein.html

Please see the above link for more information, citations and links to peer-reviewed research on this.

This is not meant to be vegetarian propaganda. Most of the research suggests that a plant-based diet is healthiest. (I was vegetarian and then vegan for a long time, and developed some health problems and vitamin deficiencies from it. So I’m not one to tout it, at least not without some conscientious vitamin supplementation.) I think a balanced diet is best — mostly plants, and a little high-quality animal protein sprinkled in, where needed.

Whoa, whoa, whoa. . . I was at first reading and thinking “some of this info is iffy,” but I stopped reading when you started talking about the necessity for combining amino acids to create complete proteins. Then you don’t explain how those combinations occur, how the body stores amino acids and for how long, how the breakdown of “complete” proteins into amino acids can be taxing, etc. Are you sourcing a 20-year-old nutrition textbook? Because that’s the last time this idea was thrown all over the place. And by the way, quinoa is not the only plant source of “complete” protein. Fluffy, waste-of-time article.

Dr. Walton, I realize you’re trying to make this readable for the average audience, but being a PhD you should know how important it is to actually read the studies in question, and explore caveats hidden in epidemiological studies (AKA every single study you cited). But i’m not just going to be a whiney commenter without coming up with some useful points, so here goes:

Perhaps you were trying to be neutral throughout (AKA here’s some controversy, but recommendations haven’t changed = story), but your writing suggests otherwise at points, such as when you label red meat as specifically containing fats + carcinogens + hormones. I appreciated that you refrained from making a blanket statement about red meat and cancer, but you didn’t cite any evidence for the “number of studies” on colon cancer (and from your phrasing i believe they’re mostly epidemiological, yes?)- but to believe that red meat *causes* one kind of cancer but no others would be pretty odd, right? You should be citing high-class RCTs to prove a point like that, if it exists.

A huge issue when delving into primary literature is the opinions of researchers and the AHA/organizations who write biased study conclusions and policies. For example, America does not eat enough protein… the average is around 16%. The RDA is .8g/kg, yet many studies indicate that double that (1.6g/kg) yields significant benefits… 50g of protein is pathetic, especially if it comes from plant sources alone which are <50% bioavailable, complete or otherwise: http://suppversity.blogspot.com/2013/06/evidence-from-metabolic-ward-16-24gkg.html (I cited a blog that cites one study. People should regularly read SuppVersity if they're serious about nutrition) Remember, these are the nutrition recommendations from a nation near the top in obesity, who vilifies an entire macronutrient on the basis of cherry-picked associations (see: Chowdhury et al 2014 for a different viewpoint)

The "high protein diets may be linked to cancer" via IGF-1 thing is… lackluster. It uses dietary survey data, then tries to substantiate this in in vitro and in vivo models that are certainly not humans. Even in the humans, the protein-mortality association flips after age 65, which physiologically makes 0 sense.

Comments section:

On complete/incomplete proteins- they would be right that you don't have to pair the proteins in the same meal, but you would be right in saying they need different plant protein sources throughout the day/week if eating from an incomplete source… or not getting enough protein because it's less bioavailable (source matters, y'know?).

As for less protein at dinnertime… what study was that? I have studies that disagree: http://www.humanengine.com/index.php/articles/nutrition/item/nutrient-timing-endures-circadian-rhythm-protein-timing?category_id=3 http://www.ncbi.nlm.nih.gov/pubmed/22330017

All in all, the article was good. But if you insist on citing experts who make very un-expert, controversial claims and not asking harder questions of them, you won't ever be a part of the health solution this nation needs.

And that’s a good study! But, the results are not saying that protein earlier in the day is better than at night, because of one point: the subjects in the SKEW group were not eating the 10g EAAs = 30g protein needed to stimulated maximal protein synthesis with every meal, but the EVEN group was. In subjects who are eating a minimum of 30g protein with every meal, as indicated by Jordan et al 2010 from the humanengine blog I cited, adding *extra* protein (like 60g at dinner) would be beneficial if 30g is still eaten at breakfast and lunch. This goes back to eating higher than the RDA, which is supposed to be the threshold for protein deficiency and not optimum healthyness. SuppVersity actually has an article on that study you cited: http://suppversity.blogspot.com/2014/01/it-does-matter-how-you-spread-your.html More on the 10g EAAs here: http://suppversity.blogspot.com/2012/12/fat-loss-principles-that-work-10g-of.html

And I disagree that there is strong evidence in favor of a plant-based diet, but that’s not saying being vegetarian is less healthy than eating animals, per se. But as for veganism, if you can’t get the nutrients from the food you’re eating… change the food you’re eating (as you did), don’t just supplement away and expect to be healthy in 20 years.